Television system



May 23, 1950 A. N. GoLDsMlTH TELEVISION SYSTEM Filed Oct. l2, 1944 AM.. E SAQ@ S Patented May 23, 1950- UNITED STATES PATENT QFFICE i Radio Corporationof America, NewYork, N. Y., a corporation of Delaware Application october V12, 1944, serial No. 5.58.4357

9 eiaims. (ci. 17e-5.4)

This invention relates to systems and methods for transmitting television images and particularly to systems wherein provisions areV made for transmitting the television images in accordance with the color representations or components from which the picture is formed. In its more particu.- lar application, the invention provides for the de.- velopment of image signals corresponding to a key image and the utilization of these key image sig,- nals to augmentand improve the color rendition and brilliancy ofv the iinally produced television images which are observable at receiving or mon.- itoring points. Y

In most presently utilized color television sys,- tems of the so-called additive type, it has been customary to employ three primary or component color images superimposed either cyclically or simultaneously to reproduce 'a color image having substantially the same colors as thevob.- ject of which the image is a representation. To provide this type of image production, signals are developed at transmitting points to repre,- sent the image in each of its selected component or primary colors. Usually, these representa,-

tions portray the image in signals representative n of red, green and blue-violet, although two-color systems have been utilized. Two-color systems usually suer from relatively inferior delity of color reproduction and thus, for the purposes o f these considerations, reference will be made to a tricolor system, although it is to be understood -that the same general principles herein involved carry over totwo-'color systems.

It is known, of course, thatY it is theoretically possible to achieve reasonably 4close to perfect color reproduction of tricolor images under ideal.- i'zed conditions. From a practical standpoint, however, these conditions are not obtained and there is actually considerable divergence from such ideal conditions due to manycauses, among which are the failure of the analyzing lters to 'meet theoretical requirements, as well as the variance in spectral sensitivity of the light .sensitive medium or camera tube of the system and, in addition to other causes, the lack of suitable 'panchromatic spectral response characteristics of the image producing medium becomes a substantial factor.

Because ofv these facts, the quality of the produced image or picture tends to vary and depart from perfection and, accordingly, to overcome lthese difficulties, the present invention seeks to provide an additional component image which Will'result from a neutralbl-ack :and white depict-i'onwhich may be termed? the key image, and

which is utilized to improve the color reproduction of the television image by increasing the brilliance in the Vhighlights and the density of theshadow areas.

`In a related application led by this applicant and identiiied as Serial No. 455,556, ledAugust 2l, 1942, now Patent No. 254232769, for a Color television system a system of a somewhat related nature has been disclosed and the use of key images to control the-image or video signal transmission hasV been set forth. The present invern- `tion is directed to the-same general field of' operations and it also dealswith a system and lmethod of improving color television images by adding to the tricolorcomponent color images a further black and white image or ak key image, which as above indicated, is vbroadly representative only of the highlights and shadows of the object orthochrornatically' viewed-that is, viewedv relative to brightness only'and irrespective'of actual color values. Alternatively, theV key imagermay correspond to infra-red, visible colored or ultra'- violet viewing oftheobject, and the selectionof the color corresponding to the brightness indicia or thev key image, while of'great" practical effect, will notl in any, way affect-the aforestated conditions.

In television systems ofi this character, in order to keep the shadows of the resultant imagel or picture deep so that they are near-black, for instance, and to keep the highlights brilliant so that-they are nearrwhite, for instance, as well as .toadd detail to the tricolor image segregation, the system is based upon an operation such that the tricolor images produced are caused alone to rproduce a chromatically correct but' slightly dirnmer image, and of 'lower gradation range, than would otherwise .be used. As is well known, the gradation range maybe taken as the ratio ofthe brightness of the most brilliant highlight of the image to the brightness of' its deepest shadow. The-key image above explainedwhen then added ,causes the shadows to remain satisfactorily deep but. ,the highlights which had previously been limitedin brightnessare brightened by the key :image so asto produce amore brilliant image with ,a longer .gradaties ranseW-hich ,Substantially im.- provestheletti1l 0f ih@ resultant-msg@ T0 @the saine extent, shadow ydetail is alsoincr'eased.

AccordingA to .the present invention, in order to Vmaintainsa suitable and desired bala-nce between 3 brightness at every part thereof and at all times in accordance with a corresponding brightness of the related or corresponding point or elemental area of the key image. In the present operation, as herein to be explained, provision is made for separating the image to be televised into such components that a key image always results, as do color separation components representative of the image in its selected component or primary colors. Separate trains of image or video signals are concurrently developed by means of separate camera tubes upon which each selected color image is projected. The scanned operations and the translation of light values into signal impulses are appropriately carried forward in such manner that like elemental points or areas of each component color image simultaneously produces a signal output. These separate signal outputs are then simultaneously and concurrently transmitted with the output level of u the image or video signal transmission representative of the chosen component or primary colors being determined in accordance with the signal output due to the key image alone.

It, therefore, becomes an object of this invention to provide an improved method by which television transmissions may be carried forward in color.

Another-object of the invention is that of providing simultaneous transmission of television images in each of the chosen component colors, together with the simultaneous transmission of signals representative of the key image with the said latter signals serving also simultaneously to modify or augment the signals representative of the separate color versions of the image.

Still further objects of the invention are those of providing for improving the detailed resolution and delineation of television image transmissions in all their parts by adding thereto the A realism and naturalness of the color reproduction, as well as increasing substantially the contrast and gradation range of the colored images as viewed at receiving and/or monitoring points.

Still other objects of the invention are those of providing for the simultaneous transmission of component color` and key images in a color television system where the scanning of all of the several image components occurs simultaneously therewith.

v Other objects of the invention are those of pro- -viding a system of color television in which one or more of the known defects of prior art systems are overcome while at the same time, providing for increased eiciency and fidelity of operation, as well as a general simplication of the apparatus.

Other objects of the invention will, of course, become apparent and suggest themselves to those skilled in the art to which the invention is directed when the following specification is read in connection with the accompanying drawing. In the drawing, the light of an optical image (not shown), of which is desired to produce a colored replica at receiving or monitoring points is projected along a path I I through a suitable optical system conventionally represented at I3 so as to come within the path of the several half-silvered mirrors-I5, Il and I9 respectively. Each of the mirror elements l5, I1 and I9 is half silvered so that substantially half of the light along the path I I passes through the mirror in the directions indicated by the arrows and the remaining half of the light is reflected from the mirrors, as indicated by the arrows adjacent to the light paths.`

The light passing along the path II which is atoaoes reflected through the mirror I5 along the path 2| may be considered as passing through a key lter element 23 to influence the light sensitive mosaic 25 of a suitable and conventionally represented camera tube 2T. The camera tube 2l is preferably, although not necessarily, of the type known in the art as a storage tube, and it provides for the conversion of impinging light into electrostatic charges which are removed and converted into signal energy pulses under the iniluence of a scanned cathode ray beam. Various tubes of this type are known and some of these have been disclosed and their operation explained in an article entitled The Orthicon, a television pickup tube, published by Messrs. Rose and Iams in the RCA Review for October 1939, commencing at page 186. Accordingly, further details of this tube and the operation thereof to produce the image or video signals are considered to be unnecessary; and, likewise, within the disclosure of this invention it is believed unnecessary to make further detailed explanation of the character of any of the mosaic electrodes utilized in any camera tube herein to be disclosed, or to illustrate any means specifically for producing and deflecting the scanning beams relative to the target mosaic.

In considering this disclosure and the several camera tubes, such as tube 21 and other tubes later to be explained in more detail, it should be understood that the scanning of the mosaics of the tubes occurs in all instances synchronously and in such manner that each mosaic is so scanned that related or homologous image points on each are simultaneously passed over by each of the scanning beams to produce the signalling output currents.

With the arrangement shown by which the light of the image passes along the paths II and 2| and through the lter 23 to the mosaic 25 of the camera tube 21, the scanning beam, when tracing the mosaic, produces the output signals which are passed along the conductor 29 and into an impliier unit 3| which may be considered as the key image amplier in that the signals amplied are representative of the key image. The amplier unit 3I is of any well known type suitably designed for the amplification of a relatively wide band of frequencies. Many amplifiers of this general type are well known in the art and further details thereof need not be discussed. Many of the theoretical considerations for amplers of this general type, however, have been set forth in the Vpublication entitled Analysis and design of video amplifiers, written by Messrs. Seeley and Kimball, and published in the RCA Review for January 1939, commencing at page 290, to which reference may herein be made. Nevertheless, any well known forms of wide band amplifiers may be used with good efficiency.

Atl is also used in a manner later to be explained to control other amplifiers of the system.

Simultaneously with the scanning of the key image in the camera tube 21, the optical image passed along the path I I which is passed through the half silvered mirror I5 and is reected from 'mirror I1 along an optical path 39 is passed through a lter element 4I which is herein identrieeliergee acquire-d Byrne mosaic 1e-due to the "ifr'rei'rigirfg "rea light, finiage signals will *be passedaloiig trie "c'oriitor '41 nand into the Ialiiplier 49 "which herein identified Aas the `red amplifier in that it amplifissignals'representav twe ofi thejr'doriponents 'of 'the image. The

amplifier te "may be or the general character 'they jreferreolj'to in "the 'discussion 'of 'the key amplia-er `a l. output-signals from' the "'ar'riplifier Isere-passedjalongtlie'-coiiiiuetorsflfandintoan jliiiipiit efiiplifrer tain arnaneriwhieh willilater flie explained. y Y

lso "simultaneously with thevactivatinor injhiieneirigiof therloo'saio"il5 bytlrered 4lrriage and the "iriosai'cz'sfby ythe keyfiniage, the image light wlilchjis passed through both of the mirrors vrl arid 'l1 to reach the mirror 1s 'aridfwhioh is-re- "fleeted Nthereijroi'ri along the 'optical wvpatri 55 fis passed throu'ghjfa Ygreen 'filter '-"5'1 fto rea'ch'the A"mdsalfcelectrodel 5`9Lof the third Icamera tube representedjat`-0|. `Wlien"a'scanning operation in thistube'is 'car'rifedlfovvari synchronously simulre'neoiisly-wiihfarrrl"eophaseaily Lwith finer-fof .the other "tribes, f'sig'rrals re're'seritingfthe green: Vimage fare passedfalo,Agtiiefooriiiiictorta'inio anrampli- "lier "65 designated as `t'lie gr'een'-ialnpliier"fin that the 'signals :amplified represent `'green liny theimage This ajr'npllier vis -of ithe -`saine general haracterlasjamplifersf 3| 'and 549 Iand the Aoutput "signals therefrom 'aref directed "through `-tl'ie 'Cdn- *ducto'r n|51 to'drtrl Ythe 'Operation of ian-'Output L'a'r'nplile'r65), las "will laterf'be explained.

`Lastly, fthe Y lig-ht 'i image 'which V`passes through ferien 'of the mirrors 115, V1111 and is is directed fuir'ougha blue-violetfiltereiemerit 1| io reach a. '-irosai'ee-leetrocle fra within thefeamero tube 15. 'Trie searir'iiiigj of -this, v"r'riosaie occurs icopliaseally seiririfsirriirliarieojiielylwith tliatiri the other-eaml`fera 'tribes alreadydescribed'so that output Slig- Lnalsfr'oln the-tube 15"-ljepresentative of the blue (tilde-ii'iole't) "image are-directed lthrough conducv'tor 11 and into Aanial'npli-le'r uni-t '19 herein'e "t 'm'e'dtheblueampli'erfin Ythat the blue' signals "areiamplifi'ed A"'llhis amplier of the same gener'al type "above explained for the amplifiers rec'eiving lights of other colors-'from the other cam- ;*ere tribes. 'The outpiitofrheamplifier is fed through 'ooridiietor el yto control "the operation of output amplifier "i8 3.`

The amplifiers `53, j 69 and 83 *amplifying the joutp'ut signals fepresfentative of red, green and fblue, vfor instance, `feed the output signals fthrgh conductorsl 81 'fand89 into signal out- -put channels designated"'respectivelyas R, fG "and B`s'o"a's t'o dentifythem astocolorinthat 'jthe'y"transiriitsignals rrepresentative of the red, thef greenaridy thec blue components respectively. "Eachfftheseanpliers"53,39land 83 may inf'lude a mxingtube conventionally Vrepresented herein respectively "as'zthe `Ytubes ^9|, '93 and l95 "Whic'h/have" the r'd Signalssupplied to the 'inner .'giid f tube ,LSI lcyvv'lyofv cOhdCtOr t5 I the green 'f signals Y'supplied "to the' inner' grid '99 by Way 'of "the "co'nductor`61 fe'edingthe; output vfrom the greenerripiifierssierra' lajstlytne innerjgrijdiul ,i' inedite'i9swhiohfreceivesjthejouipiii *of the trueiiirifierfstbytvayofloonduotor's'l.

i6 'It was above explained land 4 `it vfis fan essential "part `of the 'present inventionthatthe 'signal output 4ofthe keyfamplifier 3| lshall control Vnot only ,the key v'signal output channel iby' way lof -amplifier l35 but shall lalso -'controIfindividually `(vtliouglfi -to a Vlesser extent 'oripartially) -the amplers for the red, the green-and the blue''s'ignals. -Ac'cording`1y,`the signals fdevelo'pedfr'om the key ampli- V`fier 3| are lfed '-by Way of conductor |03 and vthrough potentilnters 105, `|'01 v'ariel |709 to inluence res'p'ectiv'e'ly Van outer grid v'element H1, '1| |3 and I'I-'S-cftheinixcrtubesgl,93 and 95 for thered-,lthe :greenandthe bluefchannels. Infac- `cordance with the settirg 'of the slider 'element of each of the Ypote'ntiomete'rs y105, `|01 and |09, the yaim'out of signals from the l--key amplifier `which is fed. into the channelsfor thered, "thc lg'reenfandblue 'signals will be determined so that fa. continuous'contrbl Within the predetermined amplitude `ranges i'sfpr'ovided for each'portion/or element of the-component colorfsignalswiththe `4 control 'being'i'n accordancewiththe spaoially homologolis portion 'of the Vkey image signals 'and v'thereby a control is achieved which will provide for f'concurrentlly varying the component color signals directly inlaccordance Withfthe key image vsignal in `the yreceiver 'instrumentality rwhich, for "instance, although-'not 'necessari1y,'=may be a 4unit fof the Y general ity-pe "described 'an'diclaimed in Amy copending applications-Serial Nos. 548,238, now Patent No. 251181,839; 548,239, now abandoned, and 5485240, n'tl/ IPatent No. 2,431,115, all filed on-Aug'ustf, 1944. Theoutput signals appearing v'in 'the different l'ou'tput channels `associated with th'e l'coridutors 31, 185, 81 and '-89 rWill appropri-` iately control theproduction Iat receiving' or monic.toring 'points fof ltheikey image, as Well as vthe 'r'ed, the -green :and @the bl'ue component Vcolor limage's whicharefthusrsimultaneously to be proi"duced land with the :production of :all of these images of lthe resultant Acombination 'thereof in -Ian additive sense, observers at `receiving points will Visualize'a :corrected image rin which Ysubfs'tantial `improvements 1n lcolor rendition,` bright- "ne'ss and gradatio'n range, as `Well as maximum highlights brightness and great detail or delineaftionare observable. .Inlthis connectionitshould V'be bornein-lmind'that:the-system herein disclosed is directly'fapplieable to the so-called additive process la'nd has such major distinctions 'from ai'range'xrients 'of vthe so-called 'subtractive ltype `wherein it has already been proposed litc provide "aso-called blacklpri'nter image which affects the image resultant byida'rkening lthe shadows with- ;outin anyway brightening the highlights which yare improvedb'y the arrangement of theiipres- `fently' disclosed system.

4In connection vvth therred, green and blue- 'violet filters il, '351 and respetivelynit 7may Ybe pointedfout thatfth'eselmay beoffsuoh densi- 'Y ties as Ato compensate largely Ifor losses' occurring idueto fthe vvusefof the h'alf-s'ilvered "mirror -sys- 'ltem which, itfiyill be appreciated, would be'such L'th'atrlly 'reieiglith of the @light intensity fin the optioelfeystem *i3 w'iureaohthe blue filter 1|, "olyone-'rfou'th jlight intensity would "reach the lgienlite'rf miavndionly' one-half l-ight would reach d*fthe "redjiilter 4 i ,i `-due to l'absorptions '-within the frriirro'r. Thus, by 'appropriate `choice of Vfilter `:dc-nfs'ity,"'orYioyrapprcpriate variations in ampli- 'ationievels j"attained in fthe 'amp-liners 48, 365

`*and 1S,clirhpensatirirrniayfbe1 had for ilterlosses. 'fljlavng'fnowvjfdescribe' the invention, what is aimed? and Ydesire'o1-'Sto be'f's'ecred" by fliettersI Pat- .ent component colors collectively constituting an vadditive color system, simultaneously producing an additional series of signals representative of .the intrinsic brightness ofthe image, controlling the signal output of the independent series of signals representative of each component color independently of Vone another under the inilulence of the signals representative of the intrinsic brightness, of thev image and simultaneously transmitting all of the intrinsic brightness and controlled component color/signals.

2. The method of developing signal wave trains for color television transmissions comprising promeans for simultaneously controlling the signal output of the plurality of developed signal wave I trains representative of each component color independently of one another under the control of the signals representative of the intrinsic brightness of the image and means for simultaneously fponent color light images of an original optical transmitting all of the controlled and the controlling signal Wave train signals.

6. The system claimed in claim 5 comprising. in addition, means to synthesize the production of all of the signals so that each signal developed instantly represents an homologous point in the initial optional image.v

7.' A system of additive color television comprising means for producing a plurality of comimage with the several color images correspondducing simultaneously a plurality of independent series of signals each` representing an optical image in different colors of apredetermined num- .ber of component colors collectively constituting an additive color system, simultaneously producing an additional series of signals representative of the visual brightness of the image, controlling the signal output of the several series of signals representative of each component color independently of one another under the influence of the signals representative of the visual brightness of the image and transmitting all of the signals simultaneously.

3. A system of color televisioncomprising y means for producing a plurality Aof-independent series of signals each representing an optical image in one only of a predetermined number of different component colorsrcollectively constituting an additive color system, means for si. multaneously producing an additional series of signals representative of the intrinsic brightness of the image, means for controlling the signal output of the independent series of signals representative of each component color independently of one another under the influence of the signals representative of the intrinsic brightness of the image and means for simultaneously transmitting all of the controlled and controlling signals.

4. A color television system comprising means A for producing` a plurality of independent signal wave trains eachrepresenting an optical image in different predetermined component colors collectively constituting the colors of an additive color system, means for simultaneously producing an additional signal Wave train representative of the intrinsic brightness of all colors of the image, means for controlling the signal output level of each of the independent signal Wave trains representative of each component color independently of one another by the signals representative of the intrinsic brightness of the image, and means for concurrently controlling transmitting media by the intrinsic brightness signals.

5. A color television system comprising a plurality of camera tubes for simultaneously producing independent signal wave trains each representing an optical image directed thereupon, a plurality of color lter elements positioned to pass light in one component color only to each camera tube Where the several chosen component colors collectively constitute an additive color system so that the signal wave train output from each camera tube represents an optical image in one component color, an additional camera tube for simultaneously producing an additional signal wave train representative of the intrinsic brightness of all colors of the image,v

ing to predetermined selected component colors collectively forming an' additive color system, means for simultaneously producing from the original optical image a second optical image representative only of the intrinsic brightness of i the original optical image, means for synchronously converting each produced color image and the intrinsic brightness image into electrica1 signaling wave trains with each Wave train instantaneously representing an homologous area of the original optical image, means for separately Y influencing the signal Wave trains representative of each separate component color image by the signal wave train representative of the intrinsic brightness of the image thereby to control the signal output for each component color and means for simultaneously energizing suitable transmission media by all of the produced signals.

8. A system of additive color television comprising means for simultaneously producing a plurality of component color light images of an original optical image with the component colors corresponding to predetermined selected component colors collectively forming an additive color system, means for simultaneously producing from the original optical image a second optical image representative only of the intrinsic brightness of the original optical image, synchronously converting the pluraliw of produced color images and the intrinsic brightness image into electrical signaling wavetrains with each wave train instantaneously representing an homologous area of the original optical image, means for separately modifying the signal Wave trains representative oi each separate component color image under the control of the signal wave train representative of the intrinsic brightness of the image thereby to control the signal output for each i Vcomponent color and means for simultaneously supplying all of the controlled and the controlling signals to suitable transmission media.

9. A system of additive color television comprising a plurality of light lter means for producing a plurality of component color light images of an original optica1 image with the component colors corresponding to predetermined selected component colors collectively forming an additive color system, means for simultaneously producing from the original optical image a second optical image representative only of the inltrinsic brightness oi the original optical image, a light responsive device positioned in the path of each produced image to respond to the light thereof, means for synchronously converting the plurality of produced color images and the inresenting an homologous area of the original optical image, means separately amplifying the signal wave trains representative of each separate component color image, means for separately controlling the amplification of each separate component image signal Wave train by the signal wave train representative of the intrinsic brightness of the image thereby to control the signal output for each component color, a load circuit connected to each amplifier output, and means l0 for simultaneously supplying all of the controlled level and the controlling signals to separate load circuits.

ALFRED N. GOLDSMITH.

10 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,253,086 Murray Aug. 19, 1941 2,375,966 Valensi May 15, 1945 2,423,769 Goldsmith July 8, 1947 FOREIGN PATENTS Number Country Date Great Britain Aug. 7, 1940 

